Method and apparatus for treating of workpieces

ABSTRACT

A workpiece having at least two elongated portions connected by a curved portion is advanced in a predetermined path so that one of its elongated portions extends lengthwise of the path and the other extends transversely thereof. As the one portion advances in the path it is treated by a stationary tool which begins to advance together with the workpiece and at the same time turns about an upright axis at the end of the one portion in order to treat the curved portion. After treating the curved portion the tool continues to advance with the workpiece but also is shifted transversely of the path to treat the other elongated portion of the workpiece.

United States Patent 1191 Stoy 1 1 Sept. 4, 1973 [54] METHOD AND APPARATUS FOR 2,073,786 3 193; Ewan... 51/38 1 1 3 2,769,280 11/19 omstoc 51/47 TREATING OF WORKPIEUS 3,488,891 1/1970 Kissling 51/35 [75] Inventor: Franz Stoy, Grafenberg, Germany [73] Assignee: Metabowerke K. G. Closs, Ranch & Primary 'f' Schnizler, Nurtingen Germany Att0rney-M1chael S. Striker PP Flo-12431017 A workpiece having at least two elongated portions connected by a curved portion is advanced in a prede- 1 i termined path so that one of its elongated portions ext t D ta [30] Foreign Applca Pnorl y a 9 tends lengthwise of the path and the other extends Germany P 5 020's transversely thereof. As the one portion advances in the path it is treated by a stationary tool which begins [52] F' 'i 32 5 25153; to advance together with the workpiece and at the [5 I] h l l i 2 Y same time turns about an upright axis at the end of the [58] he d one portion in order to treat the curved portion. After 2 k treating the curved portion the tool continues to advance with the workpiece but also is shifted transversely of the path to treat the other elongated portion [56] UNI i) i x ii:s i rrzNTs of the workpiece' TE A 3 59:1 464 7/1971 Bell 51 143 15 Clams Drawing Figures 1,493,787 5/1924 Little 51/47 UX PATENTEIJsEP 41975 i LQSHEUZLUFZ METHOD AND APPARATUS FOR TREATING OF WORKPIECES BACKGROUND OF THE INVENTION The present invention relates generally to the treating of workpieces, and more particularly to the continuous treating of workpieces. Still more particularly, the invention relates to a method for the continuous treating of advancing workpieces and to an apparatus for carrying out the method.

There are many workpieces having at least two elongated portions extending at an angle to' one another and connected by a curved portion. As an example of this, bumpers for passenger cars may be considered which usually have the main portion which later is to extend across the front of the car, and two shorter but still elongated side portions which extend usually normal to the main portion and which is connected with the same by curved portions. When such workpieces which hereafter for the sake of convenience but now in any limiting sense will be referred to as bumpers, are to be treated, for instance by being ground and/or polished, it is already known to advance them along a stationary tool which grinds and/or polishes them. In order to obtain treating of the curved portions the workpiece is pivoted about an axis such that it pivots with reference to the tool. a

To obtain a uniform surface appearance of the workpiece, it is of course necessary, as will be appreciated, that the tool will act upon the workpiece at all portions thereof for the same period of time per surface area. This means that if the workpiece is to be treated in an economically feasible manner, meaning that the elongated portions of the workpiece or bumper must move past the tool at a relatively high speed in order to save time, a substantial angular velocity must be imparted to the workpiece as it is pivoted about the tool in order to permit the tool to treat the curved portions. This, however, means that the structure supporting the workpiece during its movement is subject to quite considerable forces which in a not inconsiderable number of instances leads to damage or breakage of such structure.

As a result, the known apparatus mentioned above can advance the workpiece during processing or treating of the elongated portions thereof only at that speed which can also be utilized during pivoting of the workpiece and treating of the curved portions thereof without causing damage to the apparatus components supporting the workpiece. Because this speed is relatively small, it has been found that the known apparatus cannot be used for high-volume production, that is that its utilization is not economically feasible.

SUMMARY OF THE INVENTION It is, accordingly, a general object of the invention to overcome the disadvantages of the prior art.

More particularly, it is an object of the present invention to provide a novel method of continuously treating a workpiece of the type here under discussion, which method is not possessed of the afore-mentioned disadvantages.

A concomitant object of the invention is to provide a novel apparatus for carrying out the method, which apparatus is also not possessed of the prior-art disadvantages.

Another object of the invention is to provide such a method and apparatus which permit treating of the workpiece at a rather high and therefore economically feasible speed.

In pursuance of these objects and of others which will become apparent hereafter, one feature of the invention resides in a method of continuously treating with a tool a workpiece having at least two elongated portions connected with a curved portion. The novel method comprises the steps of orienting the workpiece relative to a predetermined path so that one of the elongated portions extends longitudinally and the other of the elongated portions extends transversely of the path. The workpiece is then continuously advanced in this path and the one elongated portion is treated with a tool which is stationary relative to the path. After treating of this one elongated portion the tool is advanced in the path together with the workpiece and is also pivoted about an axis which issubstantially concentric to the curvature of the curved portion, and during such movement the tool treats the curved portion. When the treating of the curved portion is completed, the tool continues to advance with the workpiece but is also shifted transversely of the path of the workpiece along the other elongated portion in order to treat the same.

The workpiece is thus fixedly connected with whatver transporting system is utilized and moves with the same, and only the tool is moved. Because of this, high operating speeds at uniform treating time per unit length and surface area can be obtained, so that the present invention assures not only economic operation but also a uniform surface appearance of the treated workpiece.

Furthermore, the mass of the tool is relatively small and can be controlled without difiiculty, being further capable of pivoting at the angular velocity (during treating of the curved portion) which corresponds to the speed previously used with reference to the elongated portions of the workpiece, so that during treating of the curved portion the same treating time per unit length is obtained as during treating of the elongated portions of the workpiece. This can be obtained without danger that mass forces which develop during pivoting of the tool could result in damage or breakage of any of the components involved so that economic treating of the workpiece at high operating speed is possible with the present invention.

According to one advantageous embodiment of the invention the apparatus for carrying out the method may comprise advancing means for advancing the workpiece in a predetermined path and at such orientation that one of the elongated portions of the workpiece extends longitudinally and the other elongated portion extends transversely of the path. Tool means is located adjacent the path and operative for treating the elongated portion during passage thereof past the tool means. Moving means is provided] for moving the tool in the path and also for pivoting in about an axis substantially concentric with the curvature of the curved portion, while the latter is being treated with the tool and shifting means provided for shifting the moving tool transversely of the path along the other elongated portion while it is being treated by the tool.

The moving means is in form of a suitable carriage or the like on which the pivoting unit is mounted, and in this manner it is rather simple for the tool to treat the curved portion or portions of the workpiece. Similarly, because a shifting means or unit is provided for shifting the moving tool transversely of the path while it is being advanced in the path, the portion or portions extending transversely to the path can also be treated in a simple and effective manner. Because of this possibility of three components of movement the tool can follow the contour of the workpiece without any difficulty and can treat the workpiece over the entire length thereof in a simple operating step and while the workpiece moves continuously and preferably at constant speed. The result is a highly uniform surface appearance on the treated workpiece.

It is advantageous if the pivoting radius of the pivoting unit is adjustable and if the pivoting unit pivots about a vertical pivot axis which is in the region of the center of mass of the tool, because particularly the latter provision assures that only relatively small masses must be moved, thus avoiding the development of mass forces which would be difficult to control.

The tool itself may be provided with a grinding wheel or a polishing wheel and the same be driven by a motor which is mounted on a plate. The plate can be connected via a carrier with a glide element which is movable in a guide of the pivoting unit in order to adjust the pivoting radius. The plate itself is pivotable with reference to the carrier, so that the motor with the tool can be pivoted about a horizontal axis and permit the tool to contact the workpiece in different planes. The motor itself may also be pivotable with reference to the plate in order to permit the removal of the tool which is connected with the motor from the workpiece and its engagement with the same.

According to one embodiment of the apparatus, the moving means may be a carriage which is advanceable in a housing, and include a support element guided by the carriage and having a free end on which the pivoting unit is mounted. The housing of the moving means itself may be connected with a lifting unit which can be raised and lowered on a vertically oriented support, but cannot be turned, in order to permit a vertical adjustment of the tool with reference to the workpiece. The support in turn, can be mounted on a carriage associated with the shifting means and the carriage can be shifted transversely of the path of movement of the workpiece and of the moving means via a cylinder and piston unit.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a slightly diagrammatic view of an apparatus according to the present invention;

FIG. 2 is a side-elevation of the apparatus in FIG. 1;

FIG. 3 is a top view of FIG. 1; and

FIGS. 4a-4i illustrate the sequence of operations of the apparatus in FIGS. 1 3 during treatment of the workpiece.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing the drawing now in detail it will be seen that'reference numeral 1 designates a workpiece here illustrated as an automobile bumper having one elongated portion, 28, two elongated portions 30, extending transversely of the portion 28, two curved portions 29 connecting the elongated portions 30 respectively with the portion 28 and two further curved portions 31 at the free ends of the elongated portions 30. This is clearly evident from FIG. 4a.

A transportation system 2 is provided for instance a conveyor of the chain type, the belt type or any other suitable type, and advances at constant speed in the direction towards the right in FIG. 1. Mounted in suitable manner on this transporting system 2 so as to move therewith, is the bumper 1 which is to be treated.

A tool 3, here configurated as a grinding or polishing disc, is mounted in a pivoting unit 4 which is connected with a moving station 5; athe latter in turn is connected with a shifting unit 6 for shifting laterally of the path in which the bumper l is advanced by the transportation system 2. The connection between the station 5 and the unit 6 is via a lifting unit 7 as will be discussed subsequently.

In the illustrated embodiment the transportation system 2 has a housing in which elements 9 advance in the already indicated direction, each of the elements 9 carrying one of the bumpers 1 so that the elongated portion 28 thereof extends in parallelism with the direction of advancement of the transportation system 2.

A motor It) drives the tool 3 in rotation and is connected with a plate 12 for pivoting movement about an axis 1 l; the pivoting about this axis is effected via a cylinder and piston unit 13, for instance of hydraulic or pneumatic type, having a cylinder which is fixedly connected with the plate 12 and a piston rod which is connected with the motor l0.

Plate 12 is mounted on a carrier 14 with which it can be pivoted about an axis 16 by means of an arrestable drive 15 whose construction is known per se and which permits the pivoting movement to be arrested at desired angular positions. Pivoting about the axis 16 of course also results in pivoting of the motor 10 and the tool 3 about this axis.

The carrier 14 is of angular configuration as most clearly evident from FIG. 2, and connects the tool 3 with the pivoting unit 4, or rather with a slide element 17 of the pivoting unit 4 with which the carrier 14 is rigidly connected. Element I7 is movable in a guide 18 to permit an adjustment of the pivoting radius of the tool 3, and a suitable arrestable drive is utilized for effecting the movement of the element 17. The pivoting unit 4 is pivotable about a vertical pivot axis 19 so that when such pivoting occurs, the tool 3 and the components carrying the same similarly pivot about the axis 19, a cylinder and piston unit 20 being provided for effecting such pivoting. The advancement of the tool 3 in longitudinal direction, that is in the direction of movement of the bumper l, is effected via a moving means or moving station 5. For this purpose, a carrier 21 connects the pivoting unit 4 with the station 5 and is itself mounted in a carriage 22 which is shiftable in the housing 23 of the station 5.

A lifting unit 7 has already been mentioned before, and it will be seen from FIGS. 1 3 that this unit 7 is connected with the housing 23 via a further carrier 24. The unit 7 itself is mounted on a vertically oriented support 25 in such a manner that it can be raised and lowered but cannot turn. The raising and lowering can be effected in various suitable ways which are known per se to those skilled in the art and by way of example it is mentioned that a rack and pinion drive can be employed. The support 25 itself is mounted on a carriage 26 of the shifting unit 6 which effects the movement transversely of the advancement of the workpiece 1, and which is connected with a cylinder and piston unit 27 which causes such movement.

In FIG. 4 the various stages of operation of the apparatus of FIGS. 1 3 are shown in sequence and diagrammatically. FIGS. 4a 4i always show top plan views of the workpiece 1 and of the tool 3 with its associated motor 10.

As FIG. 4a shows, the surface treating of the workpiece 1 begins by treating of one of the curved portions 31 with the tool 3. The direction of advancement of the transportation system 2 and therefore of the workpiece l is indicated by the arrow pointing towards the left in FIG. 4a. This advancement is at constant speed and, as the two arrows at the right-hand side of FIG. .40 indicate, during treatment of the curved portion 31 the unit 5 and the unit 4 are in operation so that he tool 3 advances along with the workpiece I at th same speed as the same and also pivots in clockwise direbtion in FIG. 4a.

After the curved portion 31 has been treated by th tool 3, the pivoting unit 4 is switched off, but the unit 5 continues to operate. In addition, as evident from FIG. 4b, the unit 6 is now switched on so that as the tool 3 and the workpiece 1 continue to advance with the transportation system 2, the tool 3 also moves transversely of the advancement as indicated by the arrow pointing in upward direction in FIG. 4b. During this movement, the tool 3 treats the portion 30 of the workpiece 1 as shown in FIG. 4b.

When the tool 3 reaches the end of the portion 30 the unit 6 is switched off and the pivot unit 4 is switched on again, so that, as shown in FIG. 40, the tool treats the curved portion 29 while continuing to move with the transportation system 2 (that is towards the left in FIG. 4) and also pivoting in clockwise direction. When the tool has completed the treating of the portion 29,

that is when it has turned through 90 in this instance, 1

the tool assumes the position shown in FIG. 4d, in which it is ready to treat the elongated portion 28 of the workpiece 1. At this time, as shown by the absence of arrows at the right-hand side of FIG. 4d, the units 4 and 5 are switched off, so that the tool 3 is now stationary whereas the workpiece 1 continues to advance on the transportation system 2 towards the left. This means that the portion 28 now moves at constant speed past the tool 3, being treated thereby. When the tool reaches the right-hand end (in FIG. 4) of the portion 28, the unit 4 and the unit 5 are both switched on so that the tool now advances towards the left with the workpiece 1 while being pivoted in clockwise direction and thus treating the curved portion 29 which adjoins the right hand end of the portion 28.

According to FIG. 4], the unit 4 is switched off when the treating of the curved portion 29 is completed, that is when in the illustrated embodiment, the tool has turned in clockwise direction through 90. While the unit 5 continues to operate, the unit 6 is now switched on, as indicated by the arrow at the right hand side of FIG. 4f, and moves the tool in the direction opposite to the direction in which it previously moved in the stage shown in FIG. 4b. Thus, the tool moves both with the workpiece l and transversely of the movement of the workpiece ll, treating the portion .30 thereof.

On reaching the end of the portion 30 which is adjacent the curved portion 31 of the workpiece, the unit 6 is switched off again whereas the unit 5 continues to operate as shown in FIG. 4g. The unit 4 is now switched on as indicated by the curved arrow at the right-hand side of FIG. 4g, causing the tool to pivot in clockwise direction while treating the curved portion 31.

FIG. 4!: shows the tool as having completed treating of the curved portion 31, and thus as having completed its treating of the entire workpiece 1. At this time, as is indicated by the absence of arrows at the right-hand side of FIG. 4h, the units 4 and 5 are switched off and the workpiece ll continues to move with the system 2 towards the left and out of the reach of the tool.

The tool is then moved back to its starting position as indicated in FIG. 4f and begins to repeat the sequence of FIGS. 4a 4h on a new workpiece 1'.

Of course, the various switching processes, that is the switching on and off of the units 4, 5 and 6, may be controlled and timed by a suitable control device which is not, however, illustrated, because it does not form a part of the present invention and is not in itself novel. The switching processes can also be carriedout by end switches or limit switches, which act upon control elements in form of magnetic valves, pneumatic or hydraulic cylinders. This, also is known per se and is not a part of the present invention.

It should be pointed out that as shown in FIGS. 1 and 2, in the illustrated position the tool 3 treats only one side of the workpiece (bumper) 1. To treat the opposite side and the surface intermediate these sides it is necessary to tilt the tool 3 together with its motor 10 by the use of the drive 15 about the axis 16 through either or depending on whether the other side or the surface intermediate the sides is to be treated, and during each of the thus obtained displaced positions, the tool 3, the workpiece I must again undergo the sequential treatment steps shown in FIGS. 4a 4h. However, in high speed installations this is usually accomplished in a different manner, in that an apparatus with the tool 3 positioned as shown in FIGS. 1 and 2 treats one side. of the workpiece, and downstream of this apparatus is located another apparatus similar to it, but with the tool 3 pivoted through 90, about the axis 116, so that it treats the other side of the workpiece, and downstream of this second apparatus is located still a third similar apparatus in which the tool 3 is pivoted about the axis 16 through 180 with respect to the position shown in FIGS. 1 and2, so that the tool can treat the surface of the workpiece intermediate the two sides, so that no repetitive passage of the workpiece, and readjustment of the apparatus, are necessary.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of applications differing from the types described above.

While the invention has been illustrated and described as embodied in the treating of a bumper for automobiles, it is not intended to be limited to the details I shown, since various modifications and structural changesmay be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

1. A method of continuously treating with a tool a workpiece having at least two mutually inclined elongated portions and at least one curved portion connecting said elongated portions, comprising the steps of orienting said workpiece relative to a predetermined path so that one of said elongated portions extends longitudinally and the other of said elongated portions extends transversely of said path; continuously advancing said workpiece in said path; treating said one elongated portion with a tool which is stationary relative to said path; thereupon advancing said tool in said path and pivoting it about an axis which is substantially concentric to the curvature of said curved portion while treating the latter with said tool; and then shifting the advancing tool transversely of said path along said other elongated portion while treating the same.

2. A method as defined in claim 1, wherein said workpiece and said tool are advanced in said path at constant speed.

3. A method as defined in claim 1, wherein said tool is turned through substantially 90 about said axis.

4. Apparatus for continuously treating a workpiece having at least two mutually inclined elongated portions and at least one curved portion connecting said elongated portions, comprising advancing means for advancing said workpiece in a predetermined path and at such orientation that one of said elongated portions extends longitudinally and the other of said elongated portions extends transversely of said path; tool means located adjacent said path and operative for treating said one elongated portion during passage thereof past said tool means; moving means for moving said tool in said path and for providing it about an axis which is substantially concentric with the curvature of said curved portion, while treating the latter; and shifting means for shifting the moving too] means transversely of said path along said other elongated portion while treating the same.

5. Apparatus as defined in claim 4, said moving means comprising a moving unit mounting said tool means for movement in said path and for turning movement about said axis.

6. Apparatus as defined in claim 5; said shifting means comprising a shifting unit for shifting said moving unit with said tool means transversely of said path.

7. Apparatus as defined in claim 4; further comprising adjusting means for adjusting the pivoting angle through which said tool means pivots with reference to said path.

8. Apparatus as defined in claim 4, said moving means including a pivoting unit mounting said tool means for pivoting movement about said axis.

9. Apparatus as defined in claim 4, wherein said axis is a vertical axis which passes through said tool means at least in the region of the center of mass of the same.

10. Apparatus as defined in claim 8, said tool means comprising a slide element movable in a guide of said pivoting unit, a plate connected with said element, a motor provided on said plate, and a rotary tool element movable with said slide element and driven by said motor.

11. Apparatus as defined in claim 10, said tool means further comprising a carrier connecting said plate with said slide element; and wherein said plate is pivotable with reference to that carrier.

12. Apparatus as defined in claim 10, wherein said motor is pivotable with reference to said plate.

13. Apparatus as defined in claim 5, said moving unit comprising a carriage movable in said path and a support element on said carriage and having a free end portion; and further comprising a pivoting unit for said tool means provided on said free end portion.

14. Apparatus as defined in claim 5, said path being a substantially horizontal path and said moving unit comprising a carriage movable in said path, and a lifting device for raising and lowering said carriage with reference to said path and workpiece.

15. Apparatus as defined in claim 14, said lifting unit comprising a vertically oriented support; and further comprising a shifting unit, including a transversely movable carriage movable transversely of said path and carrying said support, and a cylinder and piston unit connected with said transverse carriage for effecting the transverse movement thereof. 

1. A method of continuously treating with a tool a workpiece having at least two mutually inclined elongated portions and at least one curved portion connecting said elongated portions, comprising the steps of orienting said workpiece relative to a predetermined path so that one of said elongated portions extends longitudinally and the other of said elongated portions extends transversely of said path; continuously advancing said workpiece in said path; treating said one elongated portion with a tool which is stationary relative to said path; thereupon advancing said tool in said path and pivoting it about an axis which is substantially concentric to the curvature of said curved portion while treating the latter with said tool; and then shifting the advancing tool transversely of said path along said other elongated portion while treating the same.
 2. A method as defined in claim 1, wherein said workpiece and said tool are advanced in said path at constant speed.
 3. A method as defined in claim 1, wherein said tool is turned through substantially 90* about said axis.
 4. Apparatus for continuously treating a workpiece having at least two mutually inclined elongated portions and at least one curved portion connecting said elongated portions, comprising advancing means for advancing said workpiece in a predetermined path and at such orientation that one of said elongated portions extends longitudinally and the other of said elongated portions extends transversely of said path; tool means located adjacent said path and operative for treating said one elongated portion during passage thereof past said tool means; moving means for moving said tool in said path and for providing it about an axis which is substantially concentric with the curvature of said curved portion, while treating the latter; and shifting means for shifting the moving tool means transversely of said path along said other elongated portion while treating the same.
 5. Apparatus as defined in claim 4, said moving means comprising a moving unit mounting said tool means for movement in said path and for turning movement about said axis.
 6. Apparatus as defined in claim 5; said shifting means comprising a shifting unit for shifting said moving unit with said tool means transversely of said path.
 7. Apparatus as defined in claim 4; further comprising adjusting means for adjusting the pivoting angle through which said tool means pivots with reference to said path.
 8. Apparatus as defined in claim 4, said moving means including a pivoting unit mounting said tool means for pivoting movement about said axis.
 9. Apparatus as defined in claim 4, wherein said axis is a vertical axis which passes through said tool means at least in the region of the center of mass of the same.
 10. Apparatus as defined in claim 8, said tool means comprising a slide element movable in a guide of said pivoting unit, a plate connected with said element, a motor provided on said plate, and a rotary tool element movable with said slide element and driven by said motor.
 11. Apparatus as defined in claim 10, said tool means further comprising a carrier connecting said plate with said slide element; and wherein said plate is pivotable with reference to that carrier.
 12. Apparatus as defined in claim 10, wherein said motor is pivotable with reference to said plate.
 13. Apparatus as defined in claim 5, said moving unit comprising a carriage movable in said path and a support element on said carriage and having a free end portion; and further comprising a pivoting unit for said tool means provided on said free end portion.
 14. Apparatus as defined in claim 5, said path being a substantially horizontal path and said moving unit comprising a carriage movable in said path, and a lifting device for raising and lowering said carriage with reference to said path and workpiece.
 15. Apparatus as defined in claim 14, said lifting unit comprising a vertically oriented support; and further comprising a shifting unit, including a transversely movable carriage movable transversely of said path and carrying said support, and a cylinder and piston unit connected with said transverse carriage for effecting the transverse movement thereof. 